textproduct: Quad Cities

KEY MESSAGES

- Hot and humid conditions will be seen today with peak heat indices of 95 to 100. A heat advisory has been issued for most areas south of I-80 until 7 PM where heat indices have a 60-80% chance of exceeding 100 degrees.

- Isolated to scattered (10-40%) showers and storms are expected this afternoon and evening. Isolate severe storms are possible, mainly along/south of I-80 with damaging winds being the primary risk.

- A cold front on Monday poses a severe weather threat, with SPC issuing a Slight Risk (Level 2 out of 5) for potential damaging winds.

- Canadian wildfire smoke is possible tonight through Sunday which will mainly result in hazy skies. Air quality may be impacted tonight and Sunday across parts of northwest Illinois.

SHORT TERM /THROUGH TONIGHT/

Issued at 136 AM CDT Sat Jul 18 2026

Very warm and humid conditions continue today with heat indices of 95 to 100 for much of the area. Based on forecasted heat indices, Wet Bulb Globe Temperatures and expected pooling of moisture near the front, the heat headlines will be extended another tier of counties north but will also include Muscatine, Scott and Rock Island counties as well.

Convection this afternoon will be isolated to low end scattered (10- 30%). Diurnal heating will drive the convection and based on the timing of the front, areas along/south of I-80 have the relatively better chances of seeing rain. Where rain does occur there will be relief from the heat and humidity.

Diurnal convection will continue into the evening hours before dissipating. By 10 PM the area should be rain free for the remainder of the night with dew points slowly falling. Northerly winds are expected to bring some wildfire smoke down into northwest Illinois.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 136 AM CDT Sat Jul 18 2026

Sunday/Sunday night Assessment...high (>80%) confidence on dry and slighly less humid conditions

Canadian high pressure and northerly winds will bring a brief respite to the hot and humid conditions Sunday into Sunday night. However, the northerly winds will increase the prospects of bringing Canadian wildfire smoke into the area. A majority of the smoke will be aloft and create hazy skies. However, reductions in air quality are possible across northwest Illinois.

Monday/Monday night Assessment...high (>80%) confidence on hot and humid conditions.

Hot and humid conditions will return again on Monday as southerly flow brings moisture back into the area ahead of an approaching cold front. Based on forecasted temperatures, heat indices and WBGT the probability is high (70-80%) that much of the area will need heat headlines.

Based on the timing of the front (afternoon/evening), the Storm Prediction Center has a slight, level 2 out of 5, risk for severe storms across the entire area. The primary risk looks to be damaging winds.

Tuesday through Thursday Assessment...high (>80%) confidence of a respite from the heat and humidity

After the passage of the cold front Monday, northwest flow aloft will dominate resulting in much less humid conditions and temperatures dropping to or slightly below normal.

There will be weak disturbances in the flow aloft moving through the area on a daily basis. However, moisture will be lacking so dry conditions are expected. However, that does not rule out the possibility of a rogue diurnal shower or storm developing during peak heating each day. The disturbance on Thursday looks to be the strongest of the three days. So, if there is sufficient moisture available, some isolated (10%) diurnal convection would be possible.

Friday Assessment...low (<25%) confidence on rain chances

On Friday the global models will drag another cool front through the area. Ahead of the front, return flow will bring moisture back into the area. The model consensus has a 20 percent chance of rain. However, the MJO will be stalling due to destructive interference with the dominate background El Nino state. At the same time the MJO will be in phase 7 or 8 which correlates to lower than normal chances for rain.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 611 AM CDT Sat Jul 18 2026

A cold front will gradually move south through the area today. Light winds will generally be southwest to west this morning, then shifting north by mid morning north, and by mid afternoon south. A few showers and storms are possible north early in the period. These could offer a brief IFR visibility, but are more likely to fall apart by 12-13Z. Another round of storms are possible, near and south of I-80 this afternoon. Confidence is low on this round of storms, but with IFR conditions expected with some potential for cigs and gusty winds as well, I have placed a Prob30 in the 21-23Z time frame this afternoon/early evening. Once this brief window for storms ends, VFR weather is expected to return, with north winds of 5 to 10 kts the rest of of tonight and early Sunday.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory from noon today to 7 PM CDT this evening for IAZ067-068-076>078-087>089-098-099. IL...Heat Advisory from noon today to 7 PM CDT this evening for ILZ015-024>026-034-035. MO...Heat Advisory from noon today to 7 PM CDT this evening for MOZ009-010.